Chapter 9: Cardiac Muscle; The Heart as a Pump and Function of the Heart Valves

Question 1

The Heart; Two separate pumps

Answer 1

• Right Heart- pumps blood through the lungs
• Left Heart- pumps blood through the Peripheral organs

Question 2

Each of the heart is a pulsatile two-chamber pump composed of an?

Answer 2

atrium and ventricle

Question 3

Each atrium is a ____________ for the ventricle, helping to move blood into the ventricle

Answer 3

weak primer pump

Question 4

The ventricles then supply the main pumping force that propels the blood either;

Answer 4

1. through the pulmonary circulation by the right ventricle
2. through the peripheral circulation by the left ventricle

Question 5

special mechanisms in the heart cause a continuing succession of heart contractions called?

Answer 5

cardiac rhythmicity

Question 6

transmitting action potentials throughout the cardiac muscle to cause the heart’s rhythmical beat

Answer 6

cardiac rhythmicity

Question 7

The Heart is composed of three major types of cardiac muscle;

Answer 7

✓ atrial muscle
✓ ventricular muscle
✓ excitatory and conductive muscle fibers

Question 8

types of muscle contract in much the same way as skeletal muscle, except the duration of contraction is much longer

Answer 8

atrial and ventricular muscle

Question 9

contract only feebly because they contain few contractile fibrils

Answer 9

specialized EXCITATORY and CONDUCTIVE fibers

Question 10

they exhibit either automatic rhythmical electrical discharge in the form of action potentials or conduction of the action potentials through the heart, providing an excitatory system that controls the rhythmic beating of the heart

Answer 10

excitatory and conductive fibers

Question 11

cardiac muscle is ___________ in the same manner as in skeletal muscle

Answer 11

striated

Question 12

cardiac muscle has typical myofibrils that contain _________ and ___________ almost identical to those found in skeletal muscle

Answer 12

actin and myosin filaments

Question 13

these filaments lie side by side and slide along one another during contraction in the same manner as occurs in skeletal muscle

Answer 13

actin and myosin filaments

Question 14

the dark areas crossing the cardiac muscle fibers

Answer 14

intercalated discs

Question 15

cell membranes that separate individual cardiac muscle cells from one another

Answer 15

intercalated discs

Question 16

are made up of many individual cells connected in series and in parallel with one another

Answer 16

cardiac muscle fibers

Question 17

At each intercalated disc the cell membranes fuse with one another in such a way that they form permeable _____________ that allow rapid diffusion of ions

Answer 17

“communicating” junctions (gap junctions)

Question 18

cardiac muscle is a ____________ of many heart muscle cells in which the cardiac muscles are so interconnected that when one of these cells become excited

Answer 18

syncytium

Question 19

The heart actually is composed of two syncytiums;

Answer 19

✓ atrial syncytium
✓ ventricular syncytium

Question 20

which constitutes the walls of the two atria

Answer 20

atrial syncytium

Question 21

which constitutes the walls of the two ventricles

Answer 21

ventricular syncytium

Question 22

The atria are separated from the ventricles by fibrous tissue that surrounds the _____________ openings between the atria and ventricles

Answer 22

ventricular (A-V) valvular

Question 23

specialized conductive system

Answer 23

A-V bundle

Question 24

a bundle of conductive fibers several millimeters in diameter

Answer 24

A-V bundle

Question 25

Action potential of skeletal muscle is caused almost entirely by sudden opening of large numbers of so called?

Answer 25

fast sodium channels

Question 26

allow tremendous numbers of sodium ions to enter the skeletal muscle fiber from the extracellular fluid

Answer 26

fast sodium channels

Question 27

in cardiac muscle, the action potential is caused by opening two types of channels;

Answer 27

✓ fast sodium channels
✓ slow calcium channels

Question 28

slow calcium channels which are also called?

Answer 28

calcium-sodium channels

Question 29

a large quantity of both calcium and sodium ions flows through these channels to the interior of the cardiac muscle fiber, and this maintains a prolonged period of depolarization that cause __________ in the action potential

Answer 29

causing the plateau